Roadbed layered compaction degree real-time monitoring method based on peak acceleration of rammer
阅读说明：本技术 一种基于夯锤峰值加速度的路基分层压实度实时监测方法 (Roadbed layered compaction degree real-time monitoring method based on peak acceleration of rammer ) 是由 周志军 闫瑞朋 徐天宇 张志鹏 朱林楦 陈超然 徐甫 于 2019-10-23 设计创作，主要内容包括：本发明提供一种基于夯锤峰值加速度的路基分层压实度实时监测方法,包括：步骤1,在路基填方施工现场待补强路基土区域,选取多个夯点,多个夯点上分别进行夯击不同的次数,采集夯锤峰值加速度；步骤2,在步骤1所选定各夯点上,分多层开挖路基,测定路基各层夯后的分层压实度和分层沉降量；步骤3,绘制分层沉降量与深度的关系图,确定有效压实深度,在有效压实深度范围内建立夯锤峰值加速度与分层压实度回归关系式；步骤4,现场监测时,将夯击得到的夯锤峰值加速度代入上述步骤3所得回归关系式,得到待测路基的分层压实度。本发明在评判路基压实质量时,考虑了液压夯实机的有效压实深度,使路基整体压实度的评判变的更加精准。(The invention provides a roadbed layered compaction degree real-time monitoring method based on the peak acceleration of a rammer, which comprises the following steps: step 1, selecting a plurality of tamping points in a roadbed soil area to be reinforced on a roadbed filling construction site, respectively tamping the tamping points for different times, and collecting the peak acceleration of a tamping hammer; step 2, excavating the roadbed in multiple layers on each tamping point selected in the step 1, and measuring the layered compaction degree and the layered settlement after tamping on each layer of the roadbed; step 3, drawing a relation graph of the layered settlement amount and the depth, determining the effective compaction depth, and establishing a regression relation between the peak acceleration of the rammer and the layered compaction degree in the range of the effective compaction depth; and 4, during field monitoring, substituting the peak acceleration of the rammer obtained by ramming into the regression relational expression obtained in the step 3 to obtain the layered compaction degree of the roadbed to be detected. According to the method, when the compaction quality of the roadbed is judged, the effective compaction depth of the hydraulic compactor is considered, so that the judgment of the whole compaction degree of the roadbed is more accurate.)
1. A roadbed layered compaction degree real-time monitoring method based on the peak acceleration of a rammer is characterized by comprising the following steps:
step 1, selecting a road foundation soil area to be reinforced on a roadbed filling construction site, selecting a plurality of tamping points, respectively tamping different times on the plurality of tamping points by using a hydraulic tamper, and collecting the peak acceleration of a tamping hammer;
step 2, excavating the roadbed in multiple layers at each tamping point selected in the step 1, measuring the layered compaction degree and the layered settlement of each layer of the roadbed after tamping, and recording data;
step 3, drawing a relational graph of the layered settlement amount and the roadbed depth, determining the effective compaction depth by utilizing linear interpolation, and establishing a regression relational expression of the peak acceleration of the rammer and the layered compaction degree in the range of the effective compaction depth;
and 4, during on-site monitoring, tamping the roadbed to be detected on the roadbed filling construction site by using a hydraulic tamper, and substituting the obtained peak acceleration of the rammer into the regression relational expression obtained in the step 3 to obtain the layered compaction degree of the roadbed to be detected.
2. The method for monitoring the roadbed layered compaction degree based on the peak acceleration of the rammer according to the claim 1, wherein in the step 1, an acceleration sensor is installed on the rammer of the hydraulic rammer compactor, and the peak acceleration of the rammer is collected through the acceleration sensor.
3. The method for monitoring the layered compaction degree of the roadbed based on the peak acceleration of the rammer according to claim 2, wherein the acceleration sensor is installed at the center of the top surface of the rammer.
4. The method for monitoring the layered compaction degree of the roadbed based on the peak acceleration of the rammer according to claim 1, wherein in the step 2, after the layered excavation, a level gauge is used for measuring the layered settlement amount of the roadbed, and a sand filling method is used for measuring the layered compaction degree of the roadbed after the ramming.
5. The method for monitoring the layered compaction degree of the roadbed based on the peak acceleration of the rammer according to claim 1, wherein in the step 3, the effective compaction depth is the depth with the vertical deformation of the soil body being 5% of the settlement of the roadbed surface.
6. The method for monitoring the layered compaction degree of the roadbed based on the peak acceleration of the rammer according to claim 1, wherein before the step 4, the method further comprises a verification step of: selecting tamping points on a roadbed filling construction site, tamping by adopting a hydraulic tamper, collecting the peak acceleration of the tamping hammer, calculating according to the regression relation in the step 3 to obtain the layered compaction degree, selecting measuring points in the range of the tamping points, measuring the layered compaction degree, comparing the measured layered compaction degree with the calculated layered compaction degree, and performing the step 4 after verifying that the result is in the error range.
7. The method for monitoring the layered compaction degree of the roadbed based on the peak acceleration of the rammer according to claim 1, wherein the method further comprises a step 5 of carrying out depth weighted average on the layered compaction degree within the effective compaction depth range to obtain the average compaction degree of the roadbed.
8. The method for monitoring the roadbed layered compaction degree in real time based on the peak acceleration of the rammer according to claim 7, wherein the average compaction degree calculation formula is as follows:
in the formula:
drrepresents the effective compaction depth;
direpresenting the depth of the ith layer within the effective compaction depth range;
Kirepresenting the degree of stratified compaction of the ith layer over a range of effective compaction depths;
n represents the number of layers of the laminate.
Technical Field
The invention relates to the technical field of roadbed compaction real-time monitoring, in particular to a roadbed layered compaction real-time monitoring method based on the peak acceleration of a rammer.
Background
The hydraulic tamping method belongs to a surface layer and deep roadbed compacting method, mainly utilizes the impact force of a tamping hammer to impact and compact a soil body, the tamping energy of the tamping hammer is less than that of the traditional dynamic compaction, but the tamping frequency is high, and the hydraulic tamping machine can be divided into a forced falling hammer and a free falling hammer according to the falling mode of the tamping hammer.
The forced drop hammer is characterized in that the rammer is lifted to a preset height by hydraulic driving force and then is subjected to reverse force application immediately, the rammer impacts the ground at an accelerated speed under the action of gravity and the thrust of a hydraulic cylinder, the kinetic energy and the hydraulic energy of the rammer are transmitted to a roadbed, and the roadbed is compacted and compacted. The free falling hammer also forcibly lifts the rammer to a preset height through hydraulic pressure, but the falling process is a free falling body, the rammer converts the self gravitational potential energy into kinetic energy, then the kinetic energy impacts the roadbed below, the soil body on the surface layer of the roadbed is compacted, and the energy is continuously transferred into the roadbed.
In the early 70 s, Americans and Germans provided ideas of reflecting the compaction degree of a compacted material by the acceleration change of a mechanical action part according to the dynamic response relation between the mechanical action part and the compacted material.
Many experiments have been performed by many scholars at home and abroad, which summarizes the combination of the application of the sensing technology and the traditional experiment method, and the acceleration sensor is arranged on a mechanical action part to acquire a power signal, and the processed signal value is in numerical relation with an evaluation index obtained by the traditional experiment.
At present, the method is basically adopted for developing vehicle-mounted compaction quality monitors of vibratory rollers and hydraulic compactors, and through tests, some scholars establish the relation between the acceleration value of mechanical equipment and the reflection of soil hardness and soil dynamic elasticity modulus, some scholars establish the relation between the acceleration value of mechanical equipment and the soil compaction values CCV and CMV, and some scholars establish the relation between the acceleration value of mechanical equipment and the roadbed compaction, and the compaction quality of the soil is reflected according to the accelerations of a rammer and a roller.
However, the relation between the dynamic response of the mechanical action part and the surface layer compactness is established by the students, the equipment can only monitor the compactness of the roadbed surface in real time, and the effective compaction depth of the mechanical equipment acting on the soil body is not considered, so the result accuracy is low; the hydraulic tamper not only affects the surface soil body, but also considers the effective compaction depth when the soil body is tamped, and analyzes the layered compaction quality of the roadbed within the effective compaction depth range, and the real-time monitoring method in the aspect is not perfect.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a roadbed layered compactness real-time monitoring method based on the peak acceleration of a rammer, and the method enables the evaluation of the overall compactness of the roadbed to be more accurate.
The invention is realized by the following technical scheme:
a roadbed layered compaction degree real-time monitoring method based on the peak acceleration of a rammer comprises the following steps:
step 2, excavating the roadbed in multiple layers at each tamping point selected in the
step 3, drawing a relational graph of the layered settlement amount and the roadbed depth, determining the effective compaction depth by utilizing linear interpolation, and establishing a regression relational expression of the peak acceleration of the rammer and the layered compaction degree in the range of the effective compaction depth;
and 4, during on-site monitoring, tamping the roadbed to be detected on the roadbed filling construction site by using a hydraulic tamper, and substituting the obtained peak acceleration of the rammer into the regression relational expression obtained in the step 3 to obtain the layered compaction degree of the roadbed to be detected.
Preferably, in
Further, an acceleration sensor is installed at the center of the top surface of the rammer.
Preferably, in the step 2, after the layered excavation, a level gauge is adopted to measure the layered settlement of the roadbed, and a sand filling method is adopted to measure the layered compaction degree of the roadbed after the tamping.
Preferably, in step 3, the depth with the vertical deformation of the soil body being 5% of the settlement of the surface layer of the roadbed is used as the effective compaction depth.
Preferably, before the step 4, the method further comprises the step of verifying: selecting tamping points on a roadbed filling construction site, tamping by adopting a hydraulic tamper, collecting the peak acceleration of the tamping hammer, calculating according to the regression relation in the step 3 to obtain the layered compaction degree, selecting measuring points in the range of the tamping points, measuring the layered compaction degree, comparing the measured layered compaction degree with the calculated layered compaction degree, and performing the step 4 after verifying that the result is in the error range.
Preferably, the method further comprises a step 5 of carrying out depth weighted average on the compaction degrees of the partial layers within the effective compaction depth range to obtain the average compaction degree of the roadbed.
Further, the average degree of compaction is calculated as follows:
in the formula:
drrepresents the effective compaction depth;
direpresenting the depth of the ith layer within the effective compaction depth range;
Kirepresenting the degree of stratified compaction of the ith layer over a range of effective compaction depths;
n represents the number of layers of the laminate.
Compared with the prior art, the invention has the following beneficial technical effects:
the invention takes a hydraulic compactor as a research object and provides a novel method for monitoring the layered compaction degree of a roadbed in real time. The invention is applicable to both free drop hammer type and forced drop hammer type hydraulic tamper.
Furthermore, the invention can automatically acquire the impact acceleration of the rammer impacting the roadbed through the acceleration sensor, can monitor the compaction quality of the roadbed in real time through the peak acceleration of the rammer, and saves the labor cost.
Furthermore, the verification step can better ensure the accuracy of the result.
Furthermore, the average compaction degree of the roadbed is obtained through the layered compaction degree calculation, and the roadbed compaction quality is evaluated from the two aspects of the layered compaction degree and the average compaction degree, so that the evaluation result is more reliable.
Drawings
FIG. 1 is a graph of soil settlement versus subgrade depth for a working condition;
FIG. 2 is a graph of soil body settlement and roadbed depth under a second working condition;
FIG. 3 is a graph of soil body settlement and roadbed depth under three working conditions;
FIG. 4 is a regression plot of roadbed compaction degree of 0-0.3m and peak acceleration of the rammer under a first working condition;
FIG. 5 is a regression plot of subgrade compaction at 0.3-0.6 meters versus ram peak acceleration for the first operating condition;
FIG. 6 is a regression plot of subgrade compaction at 0.6-0.9 meters and ram peak acceleration in condition one;
FIG. 7 is a regression plot of roadbed compactedness of 0-0.3m and peak acceleration of the rammer under the second operating condition;
FIG. 8 is a regression plot of subgrade compaction at 0.3-0.6 meters and ram peak acceleration in condition two; (ii) a
FIG. 9 is a regression plot of subgrade compaction at 0.6-0.9 meters and ram peak acceleration in condition two;
FIG. 10 is a regression plot of subgrade compaction at 0-0.3 meters versus ram peak acceleration for condition three;
FIG. 11 is a regression plot of subgrade compaction at 0.3-0.6 meters and ram peak acceleration in condition three;
FIG. 12 is a regression plot of subgrade compaction at 0.6-0.9 meters versus ram peak acceleration for condition three.
In FIGS. 4 to 12, the unit g of the abscissa indicates 10m/s2。
Detailed Description
The present invention will now be described in further detail with reference to specific examples, which are intended to be illustrative, but not limiting, of the invention.
A loess subgrade layered compaction degree real-time monitoring method based on hydraulic ram peak acceleration comprises the following steps:
(1) real-time collection of peak rammer acceleration a during ramming of rammerp。
(2) In the effective compaction depth range, a functional relation between the peak acceleration of the rammer and the layered compaction degree is established, and the peak acceleration a of the rammer is usedpReal-time reflection of layered compaction degree Ki。
(3) Split layer compaction K within effective compaction depth rangeiObtaining average compactness according to roadbed depth weighted average
Meanwhile, the test scheme provided by the invention is as follows:
the method comprises the steps of installing an acceleration sensor on a rammer of the hydraulic rammer compactor, then conducting a plurality of groups of ramming tests on a roadbed to be reinforced, collecting acceleration signals of the rammer through the acceleration sensor and a computer, measuring the layered compaction degree after ramming by using a traditional method, summarizing experimental data, rejecting large data of errors and keeping effective data. By referring to a foundation treatment manual of 2000 edition of Chinese construction industry publishers, the effective compaction depth is the depth with the vertical deformation of a soil body as the tamping settlement of 5 percent of the surface of the roadbed. Finally, a regression relation between the roadbed layered compaction degree and the peak acceleration of the rammer within the effective compaction depth range is established, and the method for monitoring the roadbed layered compaction degree in real time by using the peak acceleration of the rammer of the hydraulic rammer is realized. And further, carrying out depth weighted average on the layered compaction degree in the effective compaction depth range to obtain the average compaction degree of the roadbed.
The invention establishes a regression relationship between the layered compaction degree and the peak acceleration of the rammer within the effective compaction depth range.
The relationship is as follows:
K＝Ax2+Bx+C
in the formula: k represents the layered compaction degree;
x represents the ram peak acceleration;
A. b, C denotes the coefficients in the relation.
The average compaction is given by the following relation:
in the formula:
drthe effective compaction depth of the rammer under a certain rammer drop distance and hammering number is represented;
diindicating the depth of the ith layer in the effective compaction depth range, wherein the depth of each layer is consistent with that of field filling;
Kiindicating the compaction (degree of stratified compaction) of the ith layer within the effective compaction depth range.
The real-time monitoring of the concrete compactness comprises the following steps:
step 1: selecting a roadbed soil area to be reinforced on a loess roadbed filling construction site, selecting tamping points, tamping by using a hydraulic tamper, and recording the peak acceleration of a tamping hammer;
step 2: performing layered excavation, wherein the excavation depth and the total excavation depth of each layer are consistent with those of the construction site during layered filling, measuring points are selected, the layered compaction degree of the compacted roadbed is measured by a sand filling method, the layered settlement amount of the roadbed is measured by a level gauge, and the recorded data correspond to the data recorded in the
and step 3: and (3) carrying out numerical analysis on the data measured in the step (2), drawing a relational graph of the layered settlement amount and the roadbed depth, determining the effective compaction depth by utilizing linear interpolation, and then respectively establishing a regression relational expression of the peak acceleration of the rammer and the layered compaction degree of the roadbed in the range of the effective compaction depth.
And 4, step 4: substituting the peak acceleration of the rammer when the roadbed soil to be measured is rammed in the filling construction site into the regression relational expression obtained in the step 3 to obtain the layered compaction degree of the roadbed at the point to be measured.
And 5: and in the effective compaction depth range, the compaction degrees of the divided layers are weighted and averaged according to the depth of the roadbed to obtain the average compaction degree of the roadbed.
Further comprising a verification step:
selecting a plurality of tamping points, verifying the regression relation in the step 3, firstly tamping the roadbed by using a hydraulic tamper, calculating to obtain the roadbed compactness, then selecting a measuring point, measuring the roadbed compactness by using a sand filling method, comparing with the calculated compactness, and then performing the step 4 when the verification result is within an error range.
The depth of the hole dug by the sand filling method is 30 cm.
In the step 2, the measuring point selecting method comprises the following steps: the surface layer measuring points are located in the area range of the test ramming points, and other soil layer measuring points are located in the position range right below the surface layer ramming points.
The ram drop height can be determined according to the equipment gear.
The acceleration sensor is installed in the center of the top surface of the rammer.